NITRIDOCUPRATES(I) - QUATERNARY PHASES IN THE SYSTEMS LI-CA/SR-CU-N

The crystal structures of the intermediate phases in the quaternary systems Li-Ca/Sr-Cu-N are characterized by structural units containing substitutional positions (Li1-xCux) in two-fold and linear coordination by nitrogen. The bond-lengths (Li1-xCux)-N ar e shortened with increasing Cu-content. SrLi2[(Li1-xCux)N]2. Isotype of Li4SrN2; 0 less-than-or-equal-to x less-than-or-equal-to 0.39 (I4(1)/amd; Z = 4; x = 0.39: a = 377.0(1) pm, c = 2736.8(6) pm). (Li0.61Cu0.39)-N: 188.5(3) pm. Sr[(Li1-xCux)N]: Isotype of Ba[NiN]; 0.33 less-than-or-equal-to x less-than-or-equal-to 0.52 (Pnma; Z = 12; x = 0.52: a = 900.1(3) pm, b = 1315.1(5) pm, c = 546.4(1) pm). (Li0.42Cu0.58)-N: 189.0(13) pm. Ca2{(Li1-xCux)(a)[(Li1-xCux)(b)N2]): Isotype of Sr2{Li[CoN2}; 0.03 -less-than-or-equal-to x(a) less-than-or-equal-to 0.27, 0.72 less-than-or-equal-to x(b) less-than-or-equal-to 0.80 (P4(2)/mnm; Z = 2; x(a) = 0.27/x(b) = 0.80: a = 529.3(1) pm, c = 663.1(2) pm). (Li0.73Cu0.27)(a)-N: 188.0(7) pm; (Li0.20Cu0.80)(b)-N: 186.2(7) pm. Based on the experimental results the bond-length Cu(I)-N of two-fold (linear) coordinated Cu(I) in nitrido-compounds is estimated to be 184.5(5) pm.